/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hbase.zookeeper;

import java.io.IOException;

import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.exceptions.DeserializationException;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.zookeeper.KeeperException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.shaded.protobuf.generated.RegionNormalizerProtos;

/**
 * Tracks region normalizer state up in ZK
 */
@InterfaceAudience.Private
public class RegionNormalizerTracker extends ZKNodeTracker {
    private static final Logger LOG = LoggerFactory.getLogger(RegionNormalizerTracker.class);

    public RegionNormalizerTracker(ZKWatcher watcher, Abortable abortable) {
        super(watcher, watcher.getZNodePaths().regionNormalizerZNode, abortable);
    }

    /**
     * Return true if region normalizer is on, false otherwise
     */
    public boolean isNormalizerOn() {
        byte[] upData = super.getData(false);
        try {
            // if data in ZK is null, use default of on.
            return upData == null || parseFrom(upData).getNormalizerOn();
        } catch(DeserializationException dex) {
            LOG.error("ZK state for RegionNormalizer could not be parsed " + Bytes.toStringBinary(upData));
            // return false to be safe.
            return false;
        }
    }

    /**
     * Set region normalizer on/off
     *
     * @param normalizerOn whether normalizer should be on or off
     * @throws KeeperException if a ZooKeeper operation fails
     */
    public void setNormalizerOn(boolean normalizerOn) throws KeeperException {
        byte[] upData = toByteArray(normalizerOn);
        try {
            ZKUtil.setData(watcher, watcher.getZNodePaths().regionNormalizerZNode, upData);
        } catch(KeeperException.NoNodeException nne) {
            ZKUtil.createAndWatch(watcher, watcher.getZNodePaths().regionNormalizerZNode, upData);
        }
        super.nodeDataChanged(watcher.getZNodePaths().regionNormalizerZNode);
    }

    private byte[] toByteArray(boolean isNormalizerOn) {
        RegionNormalizerProtos.RegionNormalizerState.Builder builder = RegionNormalizerProtos.RegionNormalizerState.newBuilder();
        builder.setNormalizerOn(isNormalizerOn);
        return ProtobufUtil.prependPBMagic(builder.build().toByteArray());
    }

    private RegionNormalizerProtos.RegionNormalizerState parseFrom(byte[] pbBytes) throws DeserializationException {
        ProtobufUtil.expectPBMagicPrefix(pbBytes);
        RegionNormalizerProtos.RegionNormalizerState.Builder builder = RegionNormalizerProtos.RegionNormalizerState.newBuilder();
        try {
            int magicLen = ProtobufUtil.lengthOfPBMagic();
            ProtobufUtil.mergeFrom(builder, pbBytes, magicLen, pbBytes.length - magicLen);
        } catch(IOException e) {
            throw new DeserializationException(e);
        }
        return builder.build();
    }
}
